2017 年 22 巻 2 号 p. 123-132
Several synthetic cannabinoids such as AM-2201 contain the 3-carbonyl-N-fluoropentylindole structure. This structure has fluorine positional isomers on the alkyl chain. In most cases, legal controls are placed only on the 5-fluoro analogue. Thus, differentiation of isomers is a significant issue in forensic science. In this study, we developed a method for the differentiation of positional isomers of 3-carbonyl-N-fluoropentylindole derivatives utilizing multiple-stage mass spectrometry using an ion trap tandem mass spectrometer. In addition, the analogues whose fluorine atom was replaced with a chlorine atom or hydroxyl group were also examined.
With respect to each positional isomer of fluorine and chlorine, the ion at m/z 232 or m/z 248, obtained by MS2 analysis of [M＋H]+, were selected as the precursor ions for MS3 analysis. The ion at m/z 232 and m/z 248 corresponded to the 3-carbonyl-N-fluoropentylindole and 3-carbonyl-N-chloropentylindole structures. Furthermore, the ion at m/z 212, corresponding to the de-halogenated fragments of the 3-carbonyl-N-fluoropentylindole- and 3-carbonyl-N-chloropentylindole-structures, was selected as the precursor ion for MS4 analysis. Consequently, combination of these MSn analysis achieved differentiation of all the positional isomers.
With respect to positional isomers with the hydroxyl group, however, the fragment ion at m/z 212 was not observed from the MS3 analysis of m/z 230, which corresponds to the 3-carbonyl-N-fluoropentylindole structure. Therefore, differentiation of each positional isomer was not achieved by MSn analysis.
This method is useful for the differentiation of positional isomers of 3-carbonyl-N-fluoropentylindole and 3-carbonyl-N-chloropentylindole derivatives.